1. Field of the Invention
The invention is directed to balloon catheters used in the treatment of aneurysms and other vascular diseases in a mammalian patient.
2. References
The following publications are cited in this application as superscript numbers:
1 Castaneda-Zuniga, et al., Interventional Radiology, in Vascular Embolotherapy, Part 1, 1:9-32, Williams & Wilkins, Publishers (1992)
2 Graf, et al., Compositions for Use in Embolizing Blood Vessels, U.S. Pat. No. 5,667,767, issued Sep. 16, 1997
3 Evans, et al., Cellulose Diacetate Compositions for Use in Embolizing Blood Vessels, U.S. Pat. No. 5,580,568, issued Dec. 3, 1996
4 Evans, et al., Novel Embolizing Compositions, U.S. Pat. No. 5,695,480, issued Dec. 9, 1997
5 Jones, et al., Methods for Embolizing Vascular Sites with an Embolizing Composition Comprising Dimethylsulfoxide, U.S. Pat. No. 5,830,178, issued Nov. 3, 1998
6 Whalen, et al., Novel Embolizing Compositions Comprising High Polymer Concentrations, U.S. patent application Ser. No. 09/574,379, filed May 19, 2000
7 Evans, et al., Methods for Embolizing Blood Vessels, U.S. Pat. No. 5,702,361, issued Dec. 30, 1997
8 Evans, et al., Methods for Embolizing Blood Vessels, U.S. Pat. No. 6,017,977, issued Jan. 25, 2000
9 Wallace, et al., Intracranial Stem and Method of Use, U.S. Pat. No. 6,007,573, issued Dec. 28, 1999.
10 Racchini, et al., Porous Balloon For Selective Dilation and Drug Delivery, U.S. Pat. No. 5,458,568, issued Oct. 17, 1995
11 Whalen, et al., Novel High Viscosity Embolizing Compositions, U.S. patent application Ser. No. 09/574,379, May 19, 2000
12 Szikora, et al., Endovascular Treatment of Experimental Aneurysms with Liquid Polymers: The Protective Potential of Stents, Neurosurgery, 3838(2):339-347 (1996)
13 Kinugasa, et al., Direct Thrombosis of Aneurysms with Cellulose Acetate Polymer, Part II-Preliminary Clinical Experience, J. Neurosurg., 77:501-507 (1992)
14 Kinugasa, et al., Cellulose Acetate Polymer Thrombosis for the emergency Treatment of Aneurysms: Angiographic Finding, Clinical Experience, and Histopathological Study, Neurosurgery, 34:694-701 (1994)
15 Mandai, et al., Direct Thrombosis of Aneurysms with Cellulose Acetate Polymer: Part I-Results of Thrombosis in Experimental Aneurysms, J. Neurosurg., 77:497-500 (1992)
16 Talia, et al., Bioabsorbable and Biodegradable Stents in Urology, J. Endourology, 11(6):391 (1997)
17 Wallace, et al., Intracranial Stent and Method of Use (Delivery System), U.S. application Ser. No. 08/762,110 (pending application).
All of the above references are herein incorporated by reference in their entirety to the same extent as if each individual reference was specifically and individually indicated to be incorporated herein by reference in its entirety.
3. State of the Art
Aneurysms arise in mammalian subjects and, in particular, human subjects as a result of vascular disease wherein the arterial wall weakens and, under pressure due to blood flow, the arterial wall “balloons.” Continued growth and/or eventual rupture of the ballooned arterial wall is associated with high morbidity and mortality rates. Intracranial aneurysms are of particular concern because surgical procedures to treat these aneurysms before rupture are often not feasible and further because rupture of these aneurysms can have devastating results on the patient even if the patient survives rupture. Accordingly, treatment protocols for intracranial aneurysms may be prophylactic in nature, i.e., to inhibit rupture or rerupture of the aneurysm rather than to inhibit bleeding from the ruptured aneurysm.
Methods well documented in the art to inhibit intracranial aneurysmal rupture/bleeding include the delivery into the aneurysmal sac of non-particulate agents such as metal coils which are designed to induce thrombosis after delivery to the aneurysm, thereby inhibiting blood flow into the aneurysm1; delivery of a fluid composition into the aneurysmal sac which composition solidifies in the sac to inhibit blood flow into the aneurysm2-6; or a delivery of a combination of non-particulate agents and a fluidic composition into the aneurysmal sac to inhibit blood flow into the aneurysm.7-8 
In each case, the cranial aneurysm is treated by filling the aneurysmal sac in a manner which inhibits blood flow into the sac. This reduced blood flow correlates to reductions in aneurysmal stress and, hence, a reduction in the likelihood of rupture. However, care must be taken to ensure against migration of non-particulate agents or fluid composition beyond the aneurysmal sac (which can occur, for example, by overfilling of the sac) because this can result in parent artery or distal embolization which, in turn, has its own high level of morbidity associated therewith.12
One method of containing the embolizing agent in the aneurysmal sac involves the use of a catheter having an occlusion or attenuation balloon. The catheter, and, specifically, the occlusion/attenuation balloon provided at the distal end thereof, performs the dual functions of blocking or impeding flow in the vessel during treatment, such that embolizing agent migration potential is significantly reduced, and providing a sealing wall or harrier against the neck of the aneurysmal sac, which aids in retaining the embolizing agent within the sac during its introduction.
Because the aneurysmal sac is usually associated with diseased tissue whose structural integrity is therefore compromised, it is important to minimize the exertion of pressure against the vessel. The occlusion balloon, therefore, must be designed to provide proper support against the vessel, conforming to the shape of the vessel and providing the necessary functionality associated with its use, without unduly stressing the tissue. In simple cases, wherein the aneurysmal sac is non-bifurcated and is located in a symmetrical, substantially constant-diameter vessel, this is readily accomplished with conventional balloon designs. However, in more complex vasculature, for example bifurcated, multi-branched or varying-diameter vessels, conventional designs are confronted with challenges which they do not satisfactorily meet. Specifically, these conventional designs utilize balloons, which, when inflated to the limits of safe operation—that is, to levels which do not impart unsustainable tissue deformation—fail to fully conform to the complex vessel shape, and, accordingly, fail to provide the proper amount of flow impedance or occlusion and support against the outflow of embolizing agent during treatment.